Investigators are still looking into the plane crash that claimed NASCAR legend Greg Biffle's life ... and, new video shows them looking for clues in the wreckage.
The National Transportation Safety Board released video of agents combing through the debris ... taking photos of the plane and looking in the woods surrounding the crash area.
The plane's a wreck ... broken into pieces both large and small and burned to a crisp in places. It's unclear what investigators might be able to glean from the crash site.